What are the different type of solar water heater technologies available?
Solar water heaters differ in terms of the collector technologies used and the design & construction of the system to suit specific applications.
Solar Water Heaters – Classified Based on Type of Collectors:
Basic solar water heaters are of two types depending upon the collector technology used: Flat Plate Collector (FPC) type and Evacuated Tube Collector (ETC) type.
Flat Plate Collector based solar water heater
The Flat Plate Collector consists of an insulated metallic box covered on the top with toughened glass. The metallic box contains an absorber sheet (normally made of copper) that is coated with a selective coating toincrease the absorption of solar energy. Vertical tubes made of copper, known as riser tubes are attached to the absorber and carry the water to be heated. The riser tubes are connected to two horizontal tubes called headers, one placed at the bottom and the other at the top. The bottom header is used for flow of water into the collector whereas the top header is used to take out the heated water.
Cold water enters the storage tank, fills it up and then flows to the collector through the bottom header and into the riser tubes, until all the absorber tubes and the header at the top are full. When the sun shines, the heat energy is absorbed by the absorber and transferred to the water in the riser tubes. The heated water being lighter than the cold water rises and via the top header pipe flows into the storage tank. More cold water flows into the collector, gets heated and rises to the top, and so on. This process known as the “Thermosyphon process” continues until the temperature of the water in the storage tank and the collector equalizes. Hot water is stored in the insulated storage tank and is available for use as and when required.
To view the FPC solar water heater models selling on Glowship, click here
Evacuated Tube Collector based solar water heater
The Evacuated Tube Collector consists of two co-axial glass tubes fused at both ends with air between the tubes evacuated to create vacuum that works as insulation. The outer surface of the inner tube forms the collector area and it is selectively coated to increase the absorption of solar energy.
Cold water enters the storage tank, fills it up and then flows into the individual tubes until all the tubes are full. When the sun shines, the heat energy is absorbed and transferred to the water in the inner tube. The heated water being lighter than the cold water rises and flows into the storage tank. More cold water flows into the collector, gets heated and rises to the top, and so on. This process known as the “Thermosyphon process” continues until the temperature of the water in the storage tank and the tube equalizes. Hot water is stored in the insulated storage tank and is available for use as and when required.
To view the ETC solar water heater models selling on Glowship, click here
In addition, in both these types of technologies variantsare available tosuit specific applications:
Solar Water Heaters – Classified Based on Type of Application:
Normal Applications:
Click here to view solar water heaters suitable for soft water (water hardness < 300ppm) and normal applications.
Click here to view solar water heaters suitable for hard water (water hardness 300ppm – 600ppm) and normal applications.
Click here to view solar water heaters suitable for extreme hard water (water hardness > 600ppm) and normal applications.
Pressurized Applications:
- The height of the overhead tank carrying cold water is less than 7 ft above the terrace
- High pressure hot water flow is required for various uses like jet showers, shower panels etc
- The number of hot water points are more than normal
The pressure rating of these types of systems varies from 3 bar upto 8 bar.
Click here to view solar water heaters suitable for soft water (water hardness < 300ppm) and normal applications.
Click here to view solar water heaters suitable for hard water (water hardness 300ppm – 600ppm) and normal applications.
Click here to view solar water heaters suitable for extreme hard water (water hardness > 600ppm) and normal applications.
Hard water suitable systems:
The water hardness tolerance level for the different type of systems varies from 600ppm to 1200ppm.
Click here to view solar water heaters with heat exchanger type tanks
Optional features:
The following optional features are available with all kinds of water heaters: